On an expedition to the islands, biologist Ian Stirling watched an emaciated bear swim underwater for three minutes and 10 seconds. The bear was trying to sneak up on a group of bearded seals resting on an ice floe, National Post reports. Stirling’s observation was part of a study which appeared in Polar Biology.
“The bear was in bad condition, very skinny, and was of course very desperate for food,” Rinie van Meurs, Stirling’s co-author wrote in an email.
The bear also had a long ways to go to get to the seals, some 40 to 50 meters, IFLScience reports. Without the cover of ice floes that bobbed in colder waters, the seals got the drop on the bear and escaped.
The researchers think the bears are adapting to climate change somewhat, but the problem is there’s probably not enough time for them to evolve into deep-diving creatures who don’t depend on ice in order to survive climate change, The Washington Post reports.
Hungry bears are also hunting more frequently on land and have been observed eating snow geese and caribou. They have also been recorded killing dolphins. With their unique capability of being able to spend extended periods underwater, it’s quite likely they have resorted to deeper dives.
Polar bears are known to enter a low-energy mode known as “walking hibernation” during times of food deprivation, but this doesn’t help them conserve much energy, and it’s certainly not enough to compensate for seal shortages during the summer ice melt, IFLScience reports. Also, while some polar bears are killing animals they don’t normally hunt, some populations are also moving farther north, into Arctic regions that will likely retain sea ice for longer periods.
These big bears are especially well-suited to aquatic life, and biologists have long been aware of this, National Post reports. They have a “lobulated” kidney that aids them in quickly filtering out waste products after a long dive. This specialized kidney is something they have in common with dolphins, whales, and sea otters and it isn’t found in most land-dwelling mammals, including the polar bears’ close cousin, the grizzly.
Because polar bears are so adaptable, researchers have long speculated they may be able to survive in an ice-free Arctic.
In 2014, analysis of their diets conducted by the American Museum of Natural History reported that polar bears might be more resilient than thought because they forage on land.
This is misleading, Stirling said.
“(T)here is simply not enough to eat on land to support so many large bears,” he said.
This polar bear’s deep dive is probably a reasonable approximation of how most marine mammals would have evolved, National Post reports.
Whales and dolphins are the descendants of land-dwelling creatures that developed aquatic capabilities over time. Evolution could provide polar bears with better diving skills and paws that are wider and fin-like.
However, ecological changes are happening so fast in the Arctic, that there isn’t enough time for the bears to evolve in order to avoid danger, Stirling says.
The Arctic without these magnificent bears wouldn’t really seem like the Arctic anymore.
